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  Keyless entry apparatusUSPTO Application #: 20080106375Title: Keyless entry apparatus Abstract: A keyless entry apparatus is disclosed that is capable of accurately determining whether a portable apparatus is positioned inside or outside an interface between an inner surface and an outer surface of a vehicle even when a region which is affected by crosstalk and/or in which saturation occurs exists outside or inside the vehicle. When an in-vehicle control unit detects that a portable apparatus is positioned in a region which is affected by crosstalk and/or in which saturation occurs, in the vicinities of some of a plurality of transmitting antennas, on the basis of intensity data from some of the plurality of transmitting antennas that is detected by a portable apparatus control unit, the in-vehicle control unit determines whether intensity data from the transmitting antenna that is detected by the portable apparatus is included in a data group composed of a plurality of intensity data that are transmitted from the transmitting antennas and then received by the portable apparatus when the portable apparatus is positioned along the inside of an interface between an inner surface and an outer surface of the vehicle in the region. When it is determined that the intensity data is included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned inside the vehicle. When it is determined that the intensity data is not included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned outside the vehicle. (end of abstract) Agent: Brinks Hofer Gilson & Lione - Chicago, IL, US Inventors: Satoshi Nakajima, Satoshi Hayasaka USPTO Applicaton #: 20080106375 - Class: 340 572 (USPTO) The Patent Description & Claims data below is from USPTO Patent Application 20080106375. Brief Patent Description - Full Patent Description - Patent Application Claims
CLAIM OF PRIORITY [0001]This application claims benefit of the Japanese Patent Application No. 2006-301846 filed on Nov. 7, 2006, which is hereby incorporated by reference. tions are hereby incorporated by reference. BACKGROUND [0002]1. Field of the Invention [0003]The present invention relates to a keyless entry apparatus that locks or unlocks a door by wireless communication between an in-vehicle apparatus and a portable apparatus, and more particularly, to a keyless entry apparatus capable of accurately determining whether a portable apparatus is positioned inside or outside a predetermined interface. [0004]2. Description of the Related Art [0005]A keyless entry apparatus that performs wireless communication between an in-vehicle apparatus and a portable apparatus carried by a user to lock or unlock a door of the vehicle has been known in the related art. In addition, a passive keyless entry apparatus having the following structure has been proposed: when a portable apparatus approaches a vehicle, communication is automatically performed between an in-vehicle apparatus and the portable apparatus to authenticate a unique portable apparatus ID, thereby locking or unlocking the door of the vehicle. Such a keyless entry apparatus is disclosed in U.S. Pat. No. 7,224,980 (corresponding to JP-A-2002-77972). [0006]However, in the passive keyless entry apparatus, it is important to determine whether the portable apparatus is positioned inside or outside the vehicle. Therefore, a plurality of transmitting antennas are provided in the in-vehicle apparatus. When the portable apparatus receives radio waves from the transmitting antennas provided inside the vehicle, the in-vehicle apparatus determines that the portable apparatus is positioned inside the vehicle. On the other hand, when the portable apparatus receives radio waves from the transmitting antennas provided outside the vehicle, the in-vehicle apparatus determines that the portable apparatus is positioned outside the vehicle. [0007]However, the keyless entry apparatus according to the related art does not have sufficient accuracy to determine the position of the portable apparatus. For example, when radio waves from the transmitting antennas provided inside the vehicle leak to the outside, the in-vehicle apparatus may determine that the portable apparatus is positioned inside the vehicle even though the portable apparatus is positioned outside the vehicle. On the other hand, when radio waves from the transmitting antennas provided outside the vehicle are transmitted to the inside of the vehicle, the in-vehicle apparatus may determine that the portable apparatus is positioned outside the vehicle even though the portable apparatus is positioned inside the vehicle. When the transmission power of radio waves from the transmitting antenna is lowered in order to prevent the leakage of radio waves, the portable apparatus may not receive radio waves inside the vehicle, which results in errors in the determination of the position of the portable apparatus. [0008]In order to solve this problem, the inventors have designed a keyless entry apparatus having the following structure, which is disclosed in U.S. patent application Ser. No. 11/435680 (U.S. Patent Application Publication No. 2006/0267407): a plurality of transmitting antennas sequentially transmit signals such that transmission times do not overlap each other; a portable apparatus is moved along the inside and outside of an interface between an inner surface and an outer surface of the vehicle to acquire intensity data that is transmitted from the plurality of transmitting antennas to the portable apparatus at a plurality of positions beforehand, thereby creating an internal data group and an external data group; the portable apparatus detects the intensity of signals transmitted from the plurality of transmitting antennas; and it is determined whether the intensity data is closer to the internal data group or the external data group, thereby determining the position of the portable apparatus. An interface, which is a criterion for determining the position of the portable apparatus, is not limited to the interface between the inner surface and the outer surface of the vehicle. [0009]However, the method of determining whether the intensity data acquired by the portable apparatus is close to the internal data group or the external data is complicated. [0010]A transmitter for allowing the transmitting antennas to transmit radio waves includes circuit elements for the transmitting antennas. The circuit elements generate transmission signals, and allow the transmitting antennas to transmit radios waves. However, the signals generated by the circuit elements interact with each other, and the leakage of signals occurs between adjacent signal lines for connecting the transmitter to the transmitting antennas. The leakage amounts of signals from the vehicles are different from each other, and the leakage amount mainly depends on the twist of the signal lines. Therefore, it is difficult to equalize the leakage amount of signals. [0011]Due to the leakage of signals, transmitting antennas other than a specific transmitting antenna that transmits radio waves also transmit weak radio waves. As a result, when the portable apparatus is positioned in a region that can detect the leaking radio waves, the portable apparatus receives the leaking radio waves in addition to the original radio waves, and thus received signal intensity becomes higher than the original received signal intensity. Therefore, in the method of determining whether the portable apparatus is positioned inside or outside the interface that has been proposed by the inventors, for example, when the user opens the door of the vehicle with the portable apparatus in his/her hand, the above-mentioned situation is likely to occur. When it is determined that the distance to the corresponding transmitting antenna is shorter than the actual distance, the receive signal intensity becomes higher than the original received signal intensity, and abnormal intensity data that should not be theoretically detected is measured. Specifically, for example, when three transmitting antennas transmit signals, a combination of intensity data transmitted from the three transmitting antennas corresponds to a specific point where the portable apparatus is positioned. However, when received signal intensity is higher than the original received signal intensity, the distance to the portable apparatus that corresponds to intensity data from one transmitting antenna may not overlap the position of the portable apparatus that is specified by intensity data from the other two transmitting antennas. In this case, a combination of intensity data becomes abnormal data. This may be similarly applied to the structure in which two transmitting antennas are provided. [0012]Further, when each data group is acquired beforehand and a data group for a Mahalanobis reference space is created, abnormal data may be included in data of each data group, which results in the lowering of detection accuracy. The transmission of radio waves from transmitting antennas other than a specific transmitting antenna due to the leakage of signals is called crosstalk. When the portable apparatus detects leaking radio waves in a region in the vicinity of a transmitting antenna that is provided outside the vehicle, errors in the detection of the position of the portable apparatus occur due to the crosstalk. [0013]Further, in the region in the vicinity of the transmitting antenna that is provided outside the vehicle, since the intensity of radio waves transmitted from the transmitting antenna is higher than that the receivable signal intensity of the portable apparatus, the signal intensity detected by the portable apparatus, which is a receiver side, is saturated to a constant value. In this case, the distance is not accurately calculated by the signal intensity detected by the portable apparatus, which causes errors in the detection of the position of the portable apparatus, similar to the crosstalk. SUMMARY OF THE DISCLOSURE [0014]A keyless entry apparatus includes an in-vehicle apparatus that is provided in a vehicle, and a portable apparatus. The in-vehicle apparatus includes: an in-vehicle transmitter that is connected to a plurality of transmitting antennas for transmitting request signals; an in-vehicle receiver that receives an answer signal; and an in-vehicle control unit that, when an answer signal transmitted from the portable apparatus is authenticated, performs a predetermined control process. The portable apparatus includes: a portable apparatus receiver that receives the request signals; a portable apparatus transmitter that transmits the answer signal; and a portable apparatus control unit that detects the intensity of each of the signals transmitted from the plurality of transmitting antennas of the in-vehicle apparatus. The in-vehicle control unit determines whether intensity data detected by the portable apparatus control unit is included in a data group composed of a plurality of intensity data that are transmitted from the plurality of transmitting antennas and received by the portable apparatus, when the portable apparatus is positioned on one side of a predetermined interface of the vehicle. When it is determined that the intensity data is included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned on the one side of the predetermined interface. When it is determined that the intensity data is not included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned on the other side of the predetermined interface. [0015]According to another aspect of the invention, a keyless entry apparatus includes an in-vehicle apparatus that is provided in a vehicle, and a portable apparatus. The in-vehicle apparatus includes: an in-vehicle transmitter that is connected to a plurality of transmitting antennas for transmitting request signals; an in-vehicle receiver that receives an answer signal; and an in-vehicle control unit that, when an answer signal transmitted from the portable apparatus is authenticated, performs a predetermined control process. The portable apparatus includes: a portable apparatus receiver that receives the request signals; a portable apparatus transmitter that transmits the answer signal; and a portable apparatus control unit that detects the intensity of each of the signals transmitted from the plurality of transmitting antennas of the in-vehicle apparatus. When the in-vehicle control unit detects that the portable apparatus is positioned in a predetermined limited region in the vicinities of some of the plurality of transmitting antennas on the basis of intensity data from some of the plurality of transmitting antennas that is detected by the portable apparatus control unit, the in-vehicle control unit determines whether intensity data from the other transmitting antennas that is detected by the portable apparatus is included in a limited data group composed of a plurality of intensity data that are transmitted from the other transmitting antennas and then received by the portable apparatus when the portable apparatus is positioned along the inside of an interface between an inner surface and an outer surface of the vehicle in the predetermined limited region. When it is determined that the intensity data is included in the limited data group, the in-vehicle control unit determines that the portable apparatus is positioned inside the vehicle. When it is determined that the intensity data is not included in the limited data group, the in-vehicle control unit determines that the portable apparatus is positioned outside the vehicle. [0016]In the keyless entry apparatus according to the above-mentioned aspect, preferably, the in-vehicle control unit calculates a Mahalanobis distance between the limited data group and the intensity data that is transmitted from the other transmitting antennas and detected by the portable apparatus control unit. Preferably, when the calculated Mahalanobis distance value is smaller than a boundary value of a Mahalanobis distance that is calculated beforehand and is considered as the limited data group, the in-vehicle control unit determines that the intensity data is included in the limited data group. Preferably, when the calculated Mahalanobis distance value is larger than the boundary value, the in-vehicle control unit determines that the intensity data is not included in the limited data group. [0017]According to a keyless entry apparatus of an embodiment, the in-vehicle control unit determines whether intensity data detected by the portable apparatus control unit is included in a data group composed of a plurality of intensity data that are transmitted from the plurality of transmitting antennas and received by the portable apparatus when the portable apparatus is positioned on one side of a predetermined interface of the vehicle. When it is determined that the intensity data is included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned on the one side of the predetermined interface. On the other hand, when it is determined that the intensity data is not included in the data group, the in-vehicle control unit determines that the portable apparatus is positioned on the other side of the predetermined interface. According to the above-mentioned structure, a data group for only one side of the interface is prepared, and it is determined whether acquired intensity data is included in the data group, thereby determining at which side of the interface the portable apparatus is positioned. As a result, it is possible to easily determine whether the portable apparatus is positioned inside or outside the vehicle. [0018]According to a keyless entry apparatus of another embodiment, when the in-vehicle control unit detects that the portable apparatus is positioned in a predetermined limited region in the vicinities of some of the plurality of transmitting antennas on the basis of intensity data from some of the plurality of transmitting antennas that is detected by the portable apparatus control unit, the in-vehicle control unit determines whether intensity data from the other transmitting antennas that is detected by the portable apparatus is included in a limited data group composed of a plurality of intensity data that are transmitted from the other transmitting antennas and then received by the portable apparatus when the portable apparatus is positioned along the inside of an interface between an inner surface and an outer surface of the vehicle in the predetermined limited region. When it is determined that the intensity data is included in the limited data group, the in-vehicle control unit determines that the portable apparatus is positioned inside the vehicle. When it is determined that the intensity data is not included in the limited data group, the in-vehicle control unit determines that the portable apparatus is positioned outside the vehicle. According to the above-mentioned structure, it is possible to determine whether the portable apparatus is positioned inside or outside the vehicle in a predetermined region, without using abnormal intensity data. [0019]According to the above-mentioned embodiments, in the keyless entry apparatus, the in-vehicle control unit calculates a Mahalanobis distance between the limited data group and the intensity data that is transmitted from the other transmitting antennas and detected by the portable apparatus control unit. When the calculated Mahalanobis distance value is smaller than a boundary value of a Mahalanobis distance that is calculated beforehand and is considered as the limited data group, the in-vehicle control unit determines that the intensity data is included in the limited data group. On the other hand, when the calculated Mahalanobis distance value is larger than the boundary value, the in-vehicle control unit determines that the intensity data is not included in the limited data group. According to the above-mentioned structure, it is possible to accurately determine whether the portable apparatus is positioned inside the vehicle on the basis of the Mahalanobis distance. [0020]According to the above-mentioned embodiments, in the keyless entry apparatus, when the in-vehicle control unit detects that the portable apparatus is positioned in regions other than the limited region in the vicinities of some of the plurality of transmitting antennas on the basis of the intensity data from some of the plurality of transmitting antennas that is detected by the portable apparatus, the in-vehicle control unit determines whether the intensity data that is detected by the portable apparatus control unit is closer to a first data group, which includes a plurality of intensity data that are transmitted from the plurality of transmitting antennas and then received by the portable apparatus and excludes intensity data in a predetermined limited region in the vicinities of the transmitting antennas when the portable apparatus is positioned along the outside of the interface between the inner surface and the outer surface of the vehicle, or a second data group, which includes a plurality of intensity data that are transmitted from the plurality of transmitting antennas and then received by the portable apparatus and excludes intensity data in a predetermined limited region in the vicinities of the transmitting antennas when the portable apparatus is positioned along the inside of the interface between the inner surface and the outer surface of the vehicle. The in-vehicle control unit determines whether the portable apparatus is positioned inside or outside the vehicle on the basis of the result of the determination. According to the above-mentioned structure, it is possible to accurately determine the position of the portable apparatus in regions other than the limited region. [0021]According to the above-mentioned embodiments, in the keyless entry apparatus, the in-vehicle control unit calculates the Mahalanobis distances between the intensity data detected by the portable apparatus control unit and the first and second data groups, and the in-vehicle control unit determines that the intensity data is close to the data group having a shorter Mahalanobis distance. According to the above-mentioned structure, it is possible to accurately determine the position of the portable apparatus in regions other than the predetermined limited region. Continue reading... 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